Mac Mini :: Plugged In A Tosslink Optical Cable, And Nothing Happened?

I have hooked up a 2009 Mac Mini (2.16, 4 gb RAM, SL 10.6.3) to my sony receiver.When using an analogue cable, it works, but in stereo of course. I plugged in a tosslink optical cable, and nothing happened, so I thought maybe the cable is broken, so I bought a new one. So when I plugged it in, it worked....for about 2 hours. Since then, I had no luck whatsoever, no sound, nothing, nada.I tried using the cable with my macbook, worked like a charm. Several reboots and a pram reset later, same thing, no sound. I checked the settings, but there's nothing really to change there, it's set to digital out and that's it.I even tried a ridiculously long terminal command to reset core audio, to no avail.